Question

For the reaction, at ${1000}^{o}C$
$CaC{O}_3\left(s\right)\rightleftharpoons CaO\left(s\right)+C{O}_2\left(g\right)$
$△G^o=-24kJmo{l}^{-1},p_{C{O}_2}=0.0030atm$
Hence, $△G$ at this temperature is :

• A. $-60.5kJmo{l}^{-1}$
• B. $-87.5kJmo{l}^{-1}$
• C. $+33.5kJmo{l}^{-1}$
• D. $-85.5kJmo{l}^{-1}$

Answer 1

The correct option is D $-85.5kJmo{l}^{-1}$

Given-$△G^o=-24kJmo{l}^{-1},p_{C{O}_2}=0.0030atm,T={1000}^{o}C=1273K$
$CaC{O}_3\left(s\right)\rightleftharpoons CaO\left(s\right)+C{O}_2\left(g\right)$
$K_p=P_{C{O}_2}=0.0030atm=3.0\times {10}^{-3}atm$
$△G=△G^o+2.303\times R\times T\times log{K}_p$
$=-24+2.303\times 8.314\times {10}^{-3}\times 1273\times log(3.0\times {10}^{-3})kJmo{l}^{-1}{K}^{-1}$
$=-24-61.493$
$=-85.49kJ$
hence, $△G=-85.49kJ$